With its wings stretched wide to catch the sun's energy, a Swiss-made solar-powered aircraft took off from Abu Dhabi just after daybreak Monday in a historic first attempt to fly around the world without a drop of fossil fuel.

Solar Impulse founder André Borschberg was at the controls of the single-seat aircraft when it lumbered into the air at the Al Bateen Executive Airport. Borschberg will trade off piloting with Solar Impulse co-founder Bertrand Piccard during layovers on a 35,000-kilometer (21,700-mile) journey.

Some legs of the trip, such as over the Pacific and Atlantic oceans, will mean five days and five nights of flying solo. Both pilots have been training hard for this journey, which will span 25 flight days over five months before this Spruce Goose of renewable energy returns to Abu Dhabi in late July or August.

"It is also exciting because you know, you simulate, you calculate, you imagine, but there is nothing like testing and doing it in real," Borschberg said just hours before takeoff. "I am sure we are all confident and hopefully we will be able to see each other here in five months."

The Solar Impulse 2 aircraft, a larger version of a single-seat prototype that first flew five years ago, has a wingspan of 72 meters (236 feet), larger than that of the Boeing 747. Built into the wings are 17,248 ultra-efficient solar cells that transfer solar energy to four electrical motors that power the plane's propellers. The solar cells also recharge four lithium polymer batteries.